The present invention relates to an apparatus and method for affecting a body tissue, such as the heart, at the tissue surface, for purposes of injecting material into the tissue or otherwise stimulating a desired therapeutic effect on the tissue.
Percutaneous catheter-based treatments of cardiovascular disease require that navigation of the catheter within the body be done with a mode of visualizing the catheter as it is moved within the body. The most popular mode of visualization is X-ray fluoroscopy, where an operator is able to monitor a radiopaque device as it travels within a body lumen, such as the cardiovascular system.
Recently, interventional procedures that require catheter navigation within the chambers of the heart have been developed; these include electrophysiological mapping and ablation and transmyocardial revascularization. These procedures also often require that the tip of the catheter be placed in contact with a wall of the beating heart in order to deliver the desired treatment safely. Potential complications of this procedure may be perforation of the wall when excessive force is applied or ineffective treatment due to poor tip contact. Under fluoroscopic guidance it is often difficult to assess when the catheter tip has reached the wall because live fluoroscopy does not visualize that wall itself, since it is not radiopaque. For the same reason, even after the catheter tip has reached the wall, it is difficult to determine whether the tip consistently remains in contact with the wall or if excessive force is applied to the wall. Finally, it is also difficult to determine whether the catheter tip is substantially perpendicular to the wall because fluoroscopy yields a two-dimensional image of the device in three-dimensional space.
Thus, for procedures where a medical instrument must be placed in firm but not excessive contact with an anatomical surface, there is an apparent need for a device which is able to provide information to the user of the instrument that is indicative of the existence and magnitude of the contact force. Furthermore, for procedures where the medical instrument must also be placed either perpendicular or at some selected angle to the anatomical surface, there is an apparent need for a device which is able to provide information to the user of the instrument that is indicative of the incident angle of the contact force with respect to the anatomical surface.
It is therefore an object of this invention to provide such a device for overcoming one or more of the above-mentioned problems.
It is another object of this invention to provide information to the user of a medical instrument, such as a catheter, that must be placed in contact with the surface of an anatomical structure, to increase the likelihood of safely delivering the desired treatment while reducing the possibility of inflicting perforation type injuries or providing inadequate treatment.
It is further an object of this invention to provide a method for generating information regarding whether the tip of a medical instrument, such as a catheter or probe, is in contact with a surface of a tissue or organ, and, if so, the magnitude of the contact force and the incident angle of the contact force with respect to the anatomical surface.
In summary, the present invention is an apparatus for treating a selected patient tissue or organ region, at the surface of such region. The apparatus may have an accessing tool for accessing the patient region, the accessing tool having a distal end, and a proximal end at which the tool can be manipulated to place the distal end adjacent to the patient region.
The apparatus may also have a probe carried on the distal end and defining a contact surface that may be urged against the patient region thereby creating contact pressure. The apparatus may further have at least one pressure transducer, wherein each pressure transducer may be operatively coupled to the probe and capable of producing a measurable response to the contact pressure experienced adjacent to the pressure transducer. A monitoring device may be operatively connected to each pressure transducer, for determining contact pressure. At least one effector may be provided, wherein each effector may be operatively disposed on the probe for producing a given effect on the patient region when the effector is activated. An activator may further be provided, which may be operatively connected to the effector, and by which the effector can be activated.